1. Field of the Invention
The present invention relates to a vehicle body frame of a saddle-ride-type vehicle. More particularly, to a vehicle body frame of a saddle-ride-type vehicle having a cross frame for connecting frames to each other in a vehicle width direction.
2. Description of Background Art
In a vehicle body frame of a saddle-ride-type vehicle such as a conventional motorcycle, the vehicle body frame adopts the frame structure where the vehicle body frame includes a plurality of skeletal frames arranged along a longitudinal direction of the vehicle and a cross frame for reinforcing the skeletal frames by connecting the skeletal frames to each other in a vehicle width direction. See, for example, JP-A-2000-6870. The joint structure of the cross frame disclosed in JP-A-2000-6870 includes a structure having distal end surfaces of the cross frame that are brought into contact with inner side surfaces of skeletal frames which face each other in an opposed manner in the vehicle width direction. Such contact portions are welded to each other in such a contact state. The structure may include side surfaces of the cross frame that are brought into contact with upper surfaces of the skeletal frames in an overlapping manner with the contact portions being welded to each other in such a state.
In the conventional welding disclosed in JP-A-2000-6870 where the skeletal frames and the cross frame are welded to each other, the welding adopts the joint structure where the distal end surfaces or the side surfaces of the cross frame are brought into contact with the side surfaces of the skeletal frames and outer peripheries of contact end surfaces are welded. Accordingly, a welded part having a predetermined length is necessary to ensure joining strength. As a result, to increase a length of the contact end surface provided for welding, it is necessary to increase a width or a cross-sectional size of the cross frame. Accordingly, the joint structure becomes a large factor which brings about large-sizing of the cross frame and an increase of the weight of the cross frame thus impairing a reduction in the weight of the vehicle body frame.